Descriptions

Two-year-old ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings from two Oregon seed sources were lifted three times in the fall, stored below freezing (-1.5°C), and compared to seedlings that were handled conventionally (spring lifting followed by short-term cold storage, 2-4°C). Based on patterns of budbreak in a greenhouse and after outplanting, I concluded that freezer storage could not totally substitute for natural chilling for September and October-lifted seedlings. On the other hand, November lift and stored seedlings had patterns of budbreak which were similar to seedlings that had naturally overwintered in the nursery beds. During storage, cold-hardiness, dry matter, and starch (both concentration, %, and content, mg) declined. The majority of change occurred in the first 3 months of storage. Seedlings lifted in September and stored until planting had poor root initiation (<15% with new roots after 30 days), and had less than 25% field survival in the first and second years after outplanting. November and spring-lifted seedlings had greater than 62% of seedlings with new roots and greater than 75% field survival. October-lifted seedlings were generally intermediate in response between early and late falllifted treatments. Initial root starch concentration or content at the time of planting was generally poorly related to subsequent root initiation, survival, and growth. Root starch concentration was greater in seedlings with new roots versus those without new roots, in both the greenhouse and field experiments. Seedling performance was apparently more closely associated with root initiation, and not starch. New roots improved the water status of seedlings and allowed greater conductance to water vapor.